BasicDAO
BasicDAO问题
介绍:
在apache-dbutils和Druid简化JDBC开发，还有许多的不足：
1.SQL语句是固定的，不能通过参数传入，通用性不好，需要进行改进，更方便执行增删改查操作
2.对select操作，如果有返回值，返回类型不能固定，需要使用泛型
3.将来的表很多，业务需求复杂，不可能只靠一个java类完成
BasicDAO示意图：
BasicDAO分析
1.utils包：存放JDBCUtilsDruid 工具类
2.domain包：存放javabean(Admin02类)
3.dao包：存放XxxDAO和BasicDAO(Admin02DAO类、BasicDao类)
4.text包：存放TsetDAO 测试类
1.utils包：存放JDBCUtilsDruid 工具类：
package com.jh.dao_.test;
//基于druid数据库连接池的工具类
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JDBCUtilsDruid {
private static DataSource ds;
static {//静态代码块完成ds的初始化
Properties properties = new Properties();
try {
properties.load(new FileInputStream("src\\druid.properties"));
//创建指定参数的连接池
ds = DruidDataSourceFactory.createDataSource(properties);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
//编写getConnection方法
public static Connection getConnection(){
try {
return ds.getConnection();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
//关闭连接(在数据库连接池技术中，close是使用的connection连接对象放回连接池)
public static void close(ResultSet resultSet, Statement statement,Connection connection){
try {
if(resultSet != null) {
resultSet.close();
}
if (statement != null){
statement.close();
}
if (connection != null){
connection.close();
}
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
2.domain包：存放javabean(Admin02类)：
package com.jh.dao_.domain;
//Admin02表与admin02表的记录对应
public class Admin02 {
private Integer id;
private String username;
private String password;
public Admin02() {
}
public Admin02(Integer id, String username, String password) {
this.id = id;
this.username = username;
this.password = password;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return id + " \t" + username + '\t' + password ;
}
}
3.dao包：存放XxxDAO和BasicDAO(Admin02DAO类、BasicDao类)：
Admin02DAO类：
package com.jh.dao_.dao; // import com.jh.dao_.domain.Admin02; public class Admin02DAO extends BasicDao{ //可以编写特有的方法 }
BasicDao类：
package com.jh.dao_.dao; //该类是其他DAO类的父类 import com.jh.datasource.JDBCUtilsDruid; import org.apache.commons.dbutils.QueryRunner; import org.apache.commons.dbutils.handlers.BeanHandler; import org.apache.commons.dbutils.handlers.BeanListHandler; import org.apache.commons.dbutils.handlers.ScalarHandler; import java.sql.Connection; import java.sql.SQLException; import java.util.List; public class BasicDao{//泛型指定具体的类型 //1. private QueryRunner qr = new QueryRunner(); //开发通用的DML方法 public int update(String sql,Object...parameters){ Connection connection = null; try { connection = JDBCUtilsDruid.getConnection(); int update = qr.update(connection, sql, parameters); return update; } catch (SQLException e) { throw new RuntimeException(e); }finally { JDBCUtilsDruid.close(null,null,connection); } } //返回多个对象(查询的结果是多行) /** * @param sql:sql语句，可以有？ * @param class01:传入一个类的Class对象，如Admin02.Class * @param parameters:传入?的具体值，可以是多个 * @return:根据Admin02.Class 返回对应的ArrayList集合 */ public List queryMultiply(String sql,Class class01,Object...parameters){ Connection connection = null; try { connection = JDBCUtilsDruid.getConnection(); return qr.query(connection,sql,new BeanListHandler (class01),parameters); } catch (SQLException e) { throw new RuntimeException(e); }finally { JDBCUtilsDruid.close(null,null,connection); } } //返回单行结果的通用方法 public T querySingle(String sql,Class class01,Object...parameters){ Connection connection = null; try { connection = JDBCUtilsDruid.getConnection(); return qr.query(connection,sql,new BeanHandler (class01) ,parameters); } catch (SQLException e) { throw new RuntimeException(e); }finally { JDBCUtilsDruid.close(null,null,connection); } } //查询单行单列的方法，返回单值的方法 public Object queryscalar(String sql,Object...parameters){ Connection connection = null; try { connection = JDBCUtilsDruid.getConnection(); return qr.query(connection,sql,new ScalarHandler() ,parameters); } catch (SQLException e) { throw new RuntimeException(e); }finally { JDBCUtilsDruid.close(null,null,connection); } } }
4.text包：存放TsetDAO 测试类：
package com.jh.dao_.test;
import com.jh.dao_.dao.Admin02DAO;
import com.jh.dao_.domain.Admin02;
import org.junit.jupiter.api.Test;
import java.util.List;
public class TestDAO {
//测试Admin02DAO对表admin02的crud操作
@Test
public void testAdmin02DAO(){
Admin02DAO admin02DAO = new Admin02DAO();
List admin02s = admin02DAO.queryMultiply(
"select * from admin02 where id >= ?", Admin02.class, 100);
System.out.println("查询结果...");
for (Admin02 admin02 : admin02s){
System.out.println(admin02);
}
}
//查询单行记录
@Test
public void testAdmin02DAO02(){
Admin02DAO admin02DAO = new Admin02DAO();
Object querySingle = admin02DAO.querySingle(
"select * from admin02 where id = ?", Admin02.class, 10);
System.out.println("查询单行记录...");
System.out.println(querySingle);
}
//查询单行单列
@Test
public void testAdmin02DAO03(){
Admin02DAO admin02DAO = new Admin02DAO();
Object queryscalar = admin02DAO.queryscalar("select username from admin02 where id = ?", 1);
System.out.println("查询单行单列...");
System.out.println(queryscalar);
}
//DML操作
@Test
public void testAdmin02DAO04(){
Admin02DAO admin02DAO = new Admin02DAO();
int update = admin02DAO.update("insert into admin02 values(null,'jett','123456')");
System.out.println(update > 0 ? "执行成功" : "执行没有影响表");
}
}
BasicDAO的实现
测试Admin02DAO对表admin02的crud操作：
查询单行记录：
查询DML操作：
